minor symfony#3758 [Book][Routing] Fixed typo on PHP version of a route definition (saro0h)

This PR was merged into the 2.3 branch.

Discussion
----------

[Book][Routing] Fixed typo on PHP version of a route definition

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all (or 2.3+)
| Fixed tickets | -

On http://symfony.com/doc/master/book/routing.html#advanced-routing-example, the PHP version has a wrong route name.

Commits
-------

b29abca [Book][Routing] Fixed typo on PHP version of a route definition

Author: weaverryan

book/routing.rst

@@ -778,7 +778,7 @@ routing system can be:
 
         $collection = new RouteCollection();
         $collection->add(
-            'homepage',
+            'article_show',
             new Route('/articles/{culture}/{year}/{title}.{_format}', array(
                 '_controller' => 'AcmeDemoBundle:Article:show',
                 '_format'     => 'html',